The present invention relates to a data management system and data management method appropriate for application in data management systems for searching files based on requests from, for example, client apparatus.
In the related art, computer systems are implemented where a client apparatus, host apparatus and storage apparatus are connected to a network so that files managed by the client apparatus are transmitted and received via the host apparatus and the network, and the files are stored on a hard disc within the storage apparatus.
In this kind of computer system, for example, file systems (sets of files) that are not used often are transferred from so-called high-cost hard disc drives within the storage apparatus to so-called low cost disc drives.
Further, with this kind of computer system, for example, file search apparatus are connected to a network. When there is then a file read request instructing the reading of a predetermined file from the client apparatus, the client apparatus searches for the requested file, and the file is read out from the storage apparatus to the client apparatus.
However, a search engine for the file search apparatus is usually developed and put into the form of a product by a dedicated vendor, while software for transferring files of the storage apparatus is developed and put into the form of a product by a storage apparatus vendor. The means that the interface connecting the file search apparatus and the storage apparatus is not standardized.
Because of this, at the search engine for the file search apparatus, after making a search index table constituting an index in the searching of a file, at the storage apparatus, in the event of transferring the file system, it is no longer possible to search files of the file system based on the search index table and an error therefore results. Therefore, with this kind of computer system, it is necessary to re-make the search index table in order to search files based on the search index table.
In theory, the administrator of the storage apparatus refers to the transfer history, and takes into consideration an operation where the search index table is updated every transferred file system, but there are cases where several hundred thousand files are stored in one file system of the storage apparatus. As the search index table is made in file units, it is not practical for the administrator of the storage apparatus to update the search index table.
As a result, a file management system is proposed in Japanese Patent Laid-open Publication No. 2003-280950 where not used information for file storage locations, metadata for the files and access priority information is managed, the stored files are accessed and rewriting of the files is carried out, where data access are exclusively controlled and the storage locations of files are changed based on storage location information and access priority information for files contained in the metadata.
However, in recent years from the point of view of compliance (act adherence) etc., it is necessary even for files that are used infrequently to be held for fixed periods. File systems for files that are used infrequently are therefore transferred to other storage apparatus and saved.
In the event that this kind of file system is transferred to another storage apparatus, or in the event that a file system is transferred to another storage apparatus the host apparatus is incapable of mounting, it is not possible to update the storage location information for the file system, files of the file system cannot be searched, and as a result it is not possible to read files requested by the client apparatus.